Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 51. (Budapest 1959)
Kaszanitzky, F.: Genetic relation of ore occurrence in the Western Mátra Mountains, North Eastern Hungary
inclusions. Resorbed remnants of old galena are frequent in older sphalerite, wurtzite and chalcopyrite, indicating its precedence in formation. The great lead content of older zincum minerals is due to digested bits of galena. (Grass e 11 y has demonstrated 12,23 and 15,75 per cent respectively of lead in wurtzite and 4,12 per cent in dark sphalerite.) Of the complex sulphides only bournonite occurs in galena, in the form of small elongate specks arranged approximately parallel to the lines of cleavage. Young galena is, together with light sphalerite, the most frequent ore mineral of the occurrence. It is more pressure-resistant than old galena. Even under the microscope, cleavage lines are but rarely observed. It occurs in dispersed grains as well as in thin veinlets (0,5 — 1,0 centimetre), or nodes of variable diameter. The isometric grains are of fairly uniform size. The predominating crystal form is the octahedron, combined with the hexahedron. It frequently contains older sphalerite and chalcopyrite as inclusions. It was formed prior to light sphalerite, as it is frequently replaced by the latter. Young galena is also attacked by young chalcopyrite which frequently occurs in a network of fine veinlets enmeshing galena. As contrary to old galena, the young generation contains a remarkably great amount of inclusions of complex sulphides. These were separated from galenite in the course of temperature decrease. They occur at the center of greater galena grains and especially on the surfaces limiting them towards quartz and other ore minerals. Greatest amounts occur on the common interfaces of galena and chalcopyrite grains. Beside bournonite one encounters jarnesonite, boulangerite and semseyite. Microscopic investigation has revealed no gold in young galena. Both generations of galena occur in all of the veins. Their distribution and frequency is, however, subject to some regularities. Old galena is subordinate on the level of the main gallery and above, while it is enriched on the deeper levels (—100, —200 metres). The —200 metre level carries exclusively old galena. Young galena is predominating on the upper levels (together with sphalerite). Its quantity is gradually decreasing with depth. It is absent in the Bányabérc vein. Spectral analysis of the older galena has revealed Sb, Zn, Ag, Au, Cu, Cd, Bi, Ti and Mn, while the young generation contains beside the above also Ba, Sr, As, Sn, Fe, No, Ni, Co (I. Kubovics, Analyst). Gold is very rare. Koch mentions one grain of 2 microns size from one section of old galenite. The present author has found it himself only in three specimens, along the border of old galenite, after having scanned several hundred préparâtes. Spectral analysis (I. Kubovics) has demonstrated it, however, also in young galenite and light sphalerite. Chalcopyrite I. was formed partly prior to, partly together with dark sphalerite. Excepting the lower level, it nowhere forms continuous masses. It occurs throughout in the form of digested inclusions in younger minerals, especially in dark sphalerite. The bigger inclusions are sometimes bisphenoidic in shape. Chalcopyrite occurs, however, also as a product of unmixing. In this case it is situated in rows of oriented small specks parallel or perpendicular to the boundaries of sphalerite grains. These two ore minerals show the phenomenon of rhythmic oriented unmixing. In wurtzite, chalcopyrite occurs in similar forms. It also invades older galena along lines of cleavage. Greater amounts of it occur in deeper levels of the Károly vein. It was even found in
